1. Field of the Invention
The present invention relates to a tie rod mounting structure in a center take-off type power steering apparatus for a vehicle. More particularly the invention relates to a tie rod mounting structure in a center take-off type power steering apparatus which reduces slackness in the tie rod mounting portion and improves a freedom degree of layout for the tie rod.
2. Description of the Related Art
The conventional tie rod mounting structure in the center take-off type power steering apparatus is made, for example, in the structure described in Japanese Utility Model Application Laid-Open Publication No. 61-84078. This states that a ball joint is employed for a portion in which an inner end of the tie rod is swingably connected to an end portion of a rack shaft. A joint main body portion of the ball joint is screwed and joined to the end portion of the rack shaft, whereby the inner end of the tie rod is swingably connected to the end portion of the rack shaft.
In this case, to prevent the ball joint main body from rotating around an axis of the rack shaft, thereby the screw joint being slacked, a lock washer for preventing slackness is interposed between the joint main body portion of the ball joint and the end portion of the rack shaft.
The lock washer disposed to the joint main body portion on a hexagonal surface, and disposed to the end portion of the rack shaft on a cylindrical surface. Then, a part of the portion fitting on the cylindrical surface is struck into a notch formed on an outer peripheral surface of the end portion of the rack shaft, whereby the joint main body portion is prevented from rotating around the axis of the rack shaft. Accordingly, it is intended to prevent the joint main body portion of the ball joint from being slacked with respect to the end portion of the rack shaft.
However, the means mentioned above can not be employed for the tie rod mounting portion in the center take-off type power steering apparatus. Due to the many parts necessary in the tie rod mounting portion in the center take-off type power steering apparatus, to insert a tool for striking the cylindrical surface of the lock washer into the notch in the opposing part is difficult.
Further, in the structure described in Japanese Patent Application Lad-Open Publication No. 11-99954. Since respective inner ends of a pair of right and left tie rods are respectively connected to a rack shaft by one bolt extending through a guide shoe sliding within a notch groove formed along a lengthwise direction of a gear box housing, a freedom degree of layout for a pair of right and left tie rods is limited. In addition, in this case, there is a risk that the respective inner ends of a pair of right and left tie rods are brought into contact with a dust boot.
An object of the present invention is to provide a tie rod mounting structure in a center take-off type power steering apparatus. The apparatus can solve the problems mentioned above contained in the conventional tie rod mounting structure in the center take-off type power steering apparatus. It can inexpensively prevent slackness of the tie rod mounting portion by a simple structure and improve a freedom degree of layout for the tie rod.
In accordance with the present invention, there is provided a tie rod mounting structure in a center take-off type power steering apparatus. The respective inner ends of a pair of right and left tie rods are swingably connected to a leg portion of a T-shaped connection member. Both arm portions of the T-shaped connection member are respectively connected to a rack shaft by a bolt extending through a guide shoe sliding within a notch groove formed along a lengthwise direction of a gear box housing. The respective inner ends of a pair of right and left tie rods laterally move in accordance with a lateral motion of the rack shaft while being guided by the guide shoe.